1. Field of the Invention
The present invention relates to a low-cost, durable and highly aesthetic shingle for roofing. More particularly, the present invention relates to a durable and flexible fiberglass composition shingle for roofing which is particularly configured as a ridge cover for application to the ridges, hips, and rakes of a roof where generally planar sections of the roof surface angularly intersect. Like a comparatively thick wood shake, the configuration of the present shingle gives an appearance of depth and creates shadow lines at adjacent shingles, which appearance of depth and shadows are considered among the principal aesthetically pleasing aspects of a wood shake roof. On the other hand, the present shingle provides fire protection much better than conventional wood shakes, and even better than conventional organic asphalt composition roofing, as well as a lower weight and better durability than the latter.
2. Description of the Related Art
A conventional low-cost organic asphalt composition ridge cover is known in accord with U.S. Pat. No. 3,913,294, issued Oct. 21, 1975 to B. Freiborg. The Freiborg patent is believed to teach a cover for the hips, ridges, and rakes of a roof wherein the cover includes a body of sheet organic filamentary material or felt layered first on an outer face with saturant asphalt penetrating somewhat through the felt sheet as well as saturating into the filaments of the felt, and then additionally layered with on outer asphalt layer securing a cosmetic and abrasion-resisting outer coating of granular mineral material.
The ridge cover of Freiborg is configured as an elongate trapezoid having a T-shaped slit extending along its length near the center thereof. Plural transverse score lines transect the upright of the T-shaped slit, and the ridge cover is back folded on itself at these score lines either two times or four times to provide a central thickening in the ridge cover. Primarily because the asphalt material tends to be brittle, especially when cool, the ridge cover of Freiborg while warm during manufacturing is folded lengthwise with the granular material outward. This lengthwise fold both allows shipment of the ridge cover in a compact form, and insures that any bending along the lengthwise fold which occurs in the field preparatory to installation of the cover on a roof is in the direction of unfolding the ridge cover at this lengthwise fold.
Even with these precautions, the shingle of Freiborg is frequently found at a job site and before being unfolded for installation to have been damaged in manufacture, packing, shipping, or handling and to have fissures or cracks in the layered asphaltic material, especially at the lengthwise fold. The layered construction and brittle nature of the asphaltic material apparently combine to result in a somewhat fragile ridge cover which frequently is damaged even before it can be installed on a roof.
These fissures and cracks compromises the weather protection for the organic fibrous mat or felt. Consequently, the shingle of Freiborg frequently has a service life even shorter than would be expected with a view to the materials from which the shingle is made. Of course, fissures which extend all the way through the ridge cover to form cracks therein render the ridge cover worthless. In view of the above, the brittle, fragile nature of the conventional organic composition ridge cover may be appreciated.
While the asphalt material layering the organic felt of Freiborg's ridge cover is strong and provides good strength and rigidity as installed, it is also brittle. That is, the conventional organic asphalt composition shingle provides a layered or non-uniform composition of relatively weak organic fibers, some of which are saturated by and/or embedded in a matrix of relatively strong and stiff, but sometimes brittle, saturant asphalt material. Because the organic asphalt composition material has a very limited tolerance to bending, and this tolerance is better in the unfolding direction than in the opposite direction, the cover of Freiborg may endure the limited unfolding or opening necessary in the field for installation on a roof. However, if ambient temperatures are not high enough, these conventional ridge covers may require that they be warmed in the field before they are opened for installation. Such opening or unfolding in the field, even though it is of a limited nature and is performed in the direction of greatest tolerance to folding, may crack and destroy the ridge cover taught by Freiborg if it is performed at a low temperature.
Despite the shortcomings outlined above, the ridge cover according to the Freiborg patent has been a commercially successful product for many years. However, during this time, inorganic composition roofing materials have been developed which are considerably more flexible, durable and fire resistant than the conventional asphalt composition roofing materials of organic felt layered with asphalt and mineral granules. Specifically, these improved modern roofing materials include a sheet-like mat or felt of inorganic glass fibers with a layer of coating-grade asphaltic material partially impregnating the inorganic felt.
The coating grade asphaltic material cannot saturate into the glass fibers of the felt. However, the asphaltic material does penetrate into and partially through the sheet of inorganic felt. The asphaltic material additionally may be filled, for example, with granite dust to improve the resistance of the material to ultraviolet light, or may be filled and modified (or "blown") by a steam and hot air process which modifies the viscosity and melting point temperature of the asphalt. Still alternatively, the asphaltic material may include rubberizers to improve its flexibility and reduce its tendency toward brittle fracture. In each case, however, the inorganic felt is conventionally layered with the asphaltic material and the resulting composition of fibrous material and matrix asphaltic material is not materially uniform throughout its thickness. Like the older roofing materials, an additional layer of asphalt adheres granular material to the outer surface of the roofing material to provide coloration and abrasion protection.
Importantly, these improved modern roofing materials offer a considerably greater flexibility, durability, and fire protection than conventional organic felt roofing materials. These improved roofing materials provide a composite of inorganic glass fibers which are very strong in tension and have an initial limpness or flexibility, but which will not endure sharp bending. That is, these inorganic glass fibers will fracture if subjected to a sharp bend. The felt of glass fibers is layered with and forms an intermediate composite with a matrix of asphaltic material which itself may be conventionally brittle, or may preferably be modified to be somewhat flexible. Even though the glass fibers are brittle and will fracture if bent sharply, they are somewhat flexible for small deflections and distortions of the shingle, and their very high tensile strength somewhat offsets the brittleness of the asphaltic matrix material.
These modern shingles have an improved tolerance to being walked on, and an improved tolerance to the give and take of a roof. The high-strength glass fibers of the composition tend to support the asphalt material so that it does not as easily crack from its own brittleness. As a result, the manufacturers of these roofing materials have been able to offer considerably longer roofing material warranties, in the range of 20 years, 30 years, or longer. Of course, in view of the high labor costs to re-roof a structure, the comparatively small incremental cost increases of the improved materials, and the risks of damage to structure and contents from water leakage which may result from a failed or worn out roof, these modern long-lived roofing materials have become very popular.
Consequently, fiberglass shingles have been widely adapted for roofing uses. However, the flexibility of fiberglass shingles which contributes to their greater tolerance to being walked on, and to their greater ability to endure the give and take of a building roof with changes in temperature and moisture content of the underlying structure, for example, is not an unmitigated advantage. The greater initial flexibility of fiberglass shingles may contribute to a greater susceptibility to their being caught by wind and being lifted off the roof surface. With conventional flat shingles, this wind susceptibility is generally overcome with the use of an adhesive securing the free end of each shingle to an underlying portion of a shingle below. This underlying portion of the lower shingle is secured to the roof by adjacent roofing nails and retains the upper shingle via the adhesive.
However, should securement of the shingle free end not be sufficient to withstand a high wind, the shingle end will be lifted and may be bent back over the rest of the shingle. In other words, the shingle is bent double on itself. Under these conditions, another unfortunate aspect of fiberglass shingles becomes apparent. When bent back on itself, a shingle creases and forms a sharp angle at the bend. Conventional organic mat or felt shingles with their low strength but flexible organic fibers may endure a very limited amount of this type of abuse and still remain intact. However, the brittle glass filaments in a fiberglass mat or felt fracture quickly when subjected to such a sharp back bend. Consequently, the fiberglass shingle will break at the crease, the free end will separate from the remainder of the shingle, and the shingle will cease to provide weather protection to the underlying roof.
In view of this recognized shortcoming of fiberglass shingle material, ridge covers of the type taught in the Freiborg patent, which require the material to endure sharp back bends during manufacture, have not been made of fiberglass mat or felt. Fiberglass mat layered with conventional or modified asphalt was believed simply not able to withstand the sharp bends necessary to form a ridge cover as taught by Freiborg.
Instead, roofing practice has evolved to the use of fiberglass shingles on the planar portions or fields of a roof, and in some cases, to the additional use of asphalt composition ridge covers of organic felt as taught by Freiborg. Of course, this practice results in a roof system having a durable shingle on the fields and a less durable ridge cover. Consequently, some home owners who believe that they have a roof warranty of 20 or 30 years, or longer, which warranty would apply properly to the field shingles, may discover to their dismay that the shingle manufacturer's warranty is voided by the combination in the roof system of the shorter-lived organic asphalt composition ridge covers. Also, while the field shingles may provide an Underwriters Laboratory Class "A" fire protection rating, the conventional ridge covers do not provide this high level of fire protection. Consequently, the fire protection of the roof system is seriously compromised by the presence of the conventional ridge covers.
In order to provide a complete roofing system which includes both inorganic shingles and inorganic ridge covers of equally long durability and fire protection ability, a formed high-profile ridge cover is presented by U.S. Pat. No. 4,920,721, (the '921 patent) issued May 1, 1990 to the co-inventors of the present invention. The '921 patent teaches a high-profile shingle which includes an elongate trapezoidal base of fiberglass mat fill-coated with asphaltic material, and provided with an outer coating of granular mineral. The shingle is provided with at least one lengthwise extending stiffener which helps overcome the initial flexibility of the fiberglass felt material while also resisting back bending of the shingle. A lengthwise generally obtuse bend is formed in the shingle, and a comparatively thick sealing member is provided adjacent the free end of the shingle to space it away from the roof structure or from an underlying shingle.
The base inorganic felt material of the shingle according to the '921 patent has sufficient bend tolerance to allow the formation of the lengthwise bend, which generally forms an obtuse angle, but is otherwise is treated as a stiff structure which is not distorted from its planar configuration. The base material from which this shingle is formed would not conventionally be expected to tolerate the sharp back bends involved in forming a shingle as taught by Freiborg. It may be appreciated that the design of the shingle taught by the '921 patent uses conventional fiberglass shingle material to best advantage, while compensating for its shortcomings.
Unfortunately, a shingle according to the '921 patent is also somewhat expensive to make and ship. That is, both the stiffener and the sealing member represent separate pieces to be formed and united with the remainder of the shingle. Also, the comparatively thick sealing members take up space and to a certain extent prevent the shingles nesting together in a shipping box as might be desired.